Investigation of ZrO₂-toughened Yb₂SiO₅ environmental barrier coating on Nb alloy under water-vapor corrosion at 1500 °C

To protect niobium alloy against water-vapor corrosion at high temperatures, an innovative ZrO₂-modified Yb₂SiO₅ environmental barrier coating was prepared via supersonic atmosphere plasma spraying. The service life of the modified coating (50 h) is 10 times higher than the pristine due to the higher fracture toughness (2.07 MPa∙m^1/2) to inhibit cracking during frequent thermal cycles. With exposure prolonging, the in-situ formation of (Zr,Yb)O₂ solid solution would weaken the fracture toughness of the coating by hindering the phase transformation of ZrO₂ from cubic to monoclinic, while improving the corrosion resistance of the coating by enhancing atomic bonding strength.